Bus to Muar:
From KLIA, you can go to the Main Central (Puduraya Bus Station) Kuala Lumpur then there are a lot of Express Bus going to Muar for every hour. It takes 2 hour journey from KL to Muar town area.
From Singapore, you can take a bus to Malacca (2 1/2 hours) and from Malacca, the town bus also can reach to Muar for about 1 hour.
When you come to this roundabout, this will be the gateway to the other parts of Johor.
The roads will lead to Batu Pahat/Johor Bahru, Tg Emas, Pusat Bandar, Melaka/Yong Peng.
Do choose the correct road or you will to drive a distance before you find your next-turn.